The present invention relates to esophageal probes and intratracheal tubes of the disposable variety.
Thoracic and pediatric surgical cases share common problems: the absence of suitable sites for the attachment of surface ECG electrodes; the need for continuous body core temperature monitoring; and the need to monitor heart and lung sounds. Instrumented probes have been employed to meet these clinical requirements in the past.
One example of such an esophageal probe, is shown in U.S. Pat. No. 3,951,136 to T. D. Wall. Disclosed therein is a multipurpose esophageal probe having the capability to monitor ECG, heart sounds and body core temperature. The Wall type probe has a number of deficiencies. Electrical interconnections to the ECG contacts are made via wires which pass internal to the lumen of the tube and are electrically connected at points within the lumen. When that probe is in use, it is inserted into the patient's mouth and then makes a 90.degree. bend into the esophagus. The internal wires tend to block the lumen of the probe and distort the heart sounds which can be monitored via a stethescope attached to the proximal end of the probe. In addition, when such a probe is employed for pediatric purposes, of necessity, the probe tube must have a small diameter. Under such conditions, internal wires substantially alter the heart sounds. Furthermore, when the patient either inhales or exhales the movement of the conductors within the lumen create noise which further impairs the quality of the heart and lung sounds.
Finally, the internal wires, being comprised of an insulated metallic conductor may significantly impair the flexibility of the esophageal probe. The probe's lessened flexibility renders it more difficult for the physician to properly emplace the probe.
U.S. Pat. No. 3,499,435, to Rockwell, et. al. shows another type of probe which achieves an unobstructed lumen, by emplacing the metal conductor internal to the wall of the probe. While achieving one beneficial result, the Rockwell probe tends to sacrifice the important feature of probe flexibility by this construction, and requires at least a second external electrode to obtain ECG signals.
Conductive plastics having the requisite flexibility desired for an esophageal probe are known. However, they have the undesirable characteristic of having an extremely high resistivity unless they are heavily loaded with a conductive material (e.g., carbon). For certain purposes, a high resistivity is acceptable, e.g., a grounding stripe exposed to the exterior of the probe--see U.S. Pat. No. 3,070,132 to Sheridan. However, to achieve reasonable conductivity, the plastic must be loaded with so much conductor that if it is exposed to the patient, it is likely that the conductive material will leach out into the patient--an obviously undesirable result.
Accordingly, it is the object of this invention to provide esophageal and tracheal probes which are both flexible and disposable.
Another object of this invention is to provide esophageal and tracheal probes which are inexpensive and are characterized by an unobstructed lumen.
A further object of this invention is to provide esophageal and tracheal tubes with the necessary flexibility and unobstructed air way and which also provide a means for obtaining ECG signals, body temperature, and either heart and breath sounds or respiratory rate.